1. Technical Field
This invention relates generally to optical catheter calibration, and more particularly to a catheter calibration device featuring a new and improved retainer arrangement for retaining the catheter in proximity with the calibration element.
2. Background Information
Calibration of an optical catheter, which may or may not also include calibration of the associated instrumentation, is often accomplished with a calibration element of known optical properties placed over the end portion of the catheter tube. Light propagated through the catheter tube returns from the calibration element to suitable instrumentation, with the measurements taken providing an optical characterization of the chatheter and instrumentaion. This characterization is then used to quantify subsequent measurements taken of a sample under examination.
In calibrating the catheter, it is important that the end portion of the catheter tube be retained in a preferred proximity with the calibration element, and that this be done in a sterile environment while enabling a convenient, repeatable calibration prior to catheter use. However, existing devices intended to accomplish this have certain drawbacks that need to be overcome.
For example, U.S. Pat. No. 4,322,164 to Shaw et al. describes a box that is sealed with the catheter in a dual-envelope sterilizable package so that the end portion of the catheter is located loosely in the box. In order to calibrate the catheter, the box is actuated by pressing a trigger mechanism through the package wrapper, and this causes a resilient holder to grip the catheter tube as a spring drives a calibration element in the form of a reflective calibrant material against the catheter tip.
Thus, the end portion of the catheter is placed and retained against the calibration element for calibration purposes, but only with a relatively complicated and expensive mechanical device. Therefore, it is desirable to have a new and improved arrangement for doing this--a calibration device that is less complicated and less expensive that achieves the desired function of catheter tube retention proximate the calibration element in a sterile environment enabling convenient, repeatable catheter calibration.